Does Tesla say that about the basic charge cord included with the car or the wall charger? The cords frequently get connected to 15 amp 120 volt receptacles that are GFCI protected with no issue. Not sure why using the 50 amp adapter would change that.So 110.3b is telling us to fallow the instructions from manufacture, tesla is telling clear do not use gfci, but the other 625.54 nec is asking for gfci, so on this case what you're doing? Is not a wall charger is a nema 14-50